For reconstructing bone defects in dental and orthopedic fields, autogenous bone grafts have been clinically applied as most assured method. However, it is necessary to operatively invade healthy region to collect bone grafts, and the amount of collected bone grafts is limited. In addition, function disorder may be caused in bone collected region, and post graft infection and/or bone resorption may be occurred. Therefore, there is a need for artificial bone filling materials in place of autogenous bone.
For reconstructing bone defects in dental and orthopedic fields, methods using artificial bone filling materials in place of autogenous bone have been clinically applied. However, if powdery or particulate bone filling materials are filled, there is a concern that the materials will easily leek out from the filled regions. In addition, because bone filling materials do not have shape-imparting properties when used alone, it is difficult to keep the materials retained in the bone defect regions for a certain period of time while maintaining an appropriate morphology.
To improve these disadvantages, there are trials to develop new composite materials comprising bone filling material and a polymer material. There have been reported that various polymers are used as shape-imparting agent to make a composite with bone filling material and the composite is filled into bone defects. Most of these composites use natural protein as a natural polymer material and therefore they are required to have safety including antigenicity and have not often been applied clinically.
Moreover, as artificial bone filling materials for reconstructing bone defects, calcium phosphate materials such as hydroxyapatite and tri-calcium phosphate have been clinically applied. These materials promote bone formation to replace bone tissue but often cause bone resorption after operation. Generally, bone filling materials work as scaffold for bone reconstruction but do not show active promotion of bone formation.
JP-A-2009-077789 discloses a method for easily preparing bone filling materials which comprises drying a slurry containing calcium phosphate powder to form a green body which is then pulverized and sintered.
JP-A-2009-178391 discloses bone filling materials having improved handling property during filling operation and high biocompatibility, which comprise a mixture of liquid L-oligolactic acid, liquid D-oligolactic acid and calcium phosphate powder or granule.
WO2008/102568 discloses a mixture of; a bone/cartilage formation-stimulating agent comprising sulfated galactosaminoglycan having 0.6 or more sulfate ester groups on average per one constituent monosaccharide or a salt thereof as an active ingredient; and a factor having a bone/cartilage formation-stimulating activity or a bone filling material (BMP, TGF-β, FGF, IGF, insulin, PDGF, HGF, midkine, pleiotrophin, collagen, gelatin, proteoglycan, fibronectin, osteocalcin, osteopontin, osteonectin, bone sialoprotein, hydroxyapatite, dicalcium phosphate anhydride, dicalcium phosphate dihydrate, α-tricalcium phosphate, amorphous calcium phosphate, octacalcium phosphate, β-tricalcium phosphate, PLLA, PLGA, titanium, decalcified bone, autogenous bone, etc.).